Warn on <literal>.asUInt|.asSInt(_: Int) (backport #4764)

[chiselbot]

Fixes #4733

Unfortunately, this is really hard to write a unit test for, but I did manually check it works (and it's using the same approach as we have been using for .U and .S). I'm also not sure that this is the best fix for 4733, but it works.

FYI @tymcauley

Contributor Checklist

• Did you add Scaladoc to every public function/method?
• Did you add at least one test demonstrating the PR?
• Did you delete any extraneous printlns/debugging code?
• Did you specify the type of improvement?
• Did you add appropriate documentation in docs/src?
• Did you request a desired merge strategy?
• Did you add text to be included in the Release Notes for this change?

Type of Improvement

• API deprecation

Desired Merge Strategy

• Squash

Release Notes

The user probably forgot .W. Apply the same technique as used for .U|.S.

Reviewer Checklist (only modified by reviewer)

• Did you add the appropriate labels? (Select the most appropriate one based on the "Type of Improvement")
• Did you mark the proper milestone (Bug fix: 3.6.x, 5.x, or 6.x depending on impact, API modification or big change: 7.0)?
• Did you review?
• Did you check whether all relevant Contributor checkboxes have been checked?
• Did you do one of the following when ready to merge:
  • Squash: You/ the contributor Enable auto-merge (squash) and clean up the commit message.
  • Merge: Ensure that contributor has cleaned up their commit history, then merge with Create a merge commit.

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This is an automatic backport of pull request #4764 done by [Mergify](https://mergify.com).